Revert "[entropy.db] drop isPackageScopeAvailable(), unused"

This reverts commit 492ace12e8.

lib/entropy/db/__init__.py

@@ -4787,6 +4787,21 @@ class EntropyRepository(EntropyRepositoryBase):
             return frozenset((y for x, y in data))
         return data
 
+    def isPackageScopeAvailable(self, atom, slot, revision):
+        """
+        Reimplemented from EntropyRepositoryBase.
+        """
+        searchdata = (atom, slot, revision,)
+        cur = self._cursor().execute("""
+        SELECT idpackage FROM baseinfo
+        where atom = (?)  AND slot = (?) AND revision = (?) LIMIT 1
+        """, searchdata)
+        rslt = cur.fetchone()
+
+        if rslt: # check if it's masked
+            return self.maskFilter(rslt[0])
+        return -1, 0
+
     def isBranchMigrationAvailable(self, repository, from_branch, to_branch):
         """
         Reimplemented from EntropyRepositoryBase.

lib/entropy/db/skel.py

@@ -3517,6 +3517,23 @@ class EntropyRepositoryBase(TextInterface, EntropyRepositoryPluginStore):
         """
         raise NotImplementedError()
 
+    def isPackageScopeAvailable(self, atom, slot, revision):
+        """
+        Return whether given package scope is available.
+        Also check if package found is masked and return masking reason
+        identifier.
+
+        @param atom: package atom string
+        @type atom: string
+        @param slot: package slot string
+        @type slot: string
+        @param revision: entropy package revision
+        @type revision: int
+        @return: tuple composed by (package_id or -1, idreason or 0,)
+        @rtype: tuple
+        """
+        raise NotImplementedError()
+
     def isBranchMigrationAvailable(self, repository, from_branch, to_branch):
         """
         Returns whether branch migration metadata given by the provided key